In many industries where products are sold in cans or other types of containers, for instance the food industry and the chemical industry, the product often includes components that are flowable materials. For example, in the food industry, granular flowable materials such as salt, sugar, and other spices are necessary ingredients in canned products. In the paint industry, flowable materials in the form of dyes or other property effecting compositions are normally added to the base composition. In both cases, the accuracy with which the flowable material is introduced into the container is a primary concern. With the advent of advanced automation in container filling operations, rather than formulating the product to be packaged in a batch mode by adding individual ingredients to a large tank and then feeding the formulated product to the individual containers, the products are formulated by adding the individual ingredients to the container itself as the container is quickly passed by multiple stations, each corresponding to an individual ingredient in the final product. Generally, the speed at which these automated container filling operations can operate has been limited by the speed at which small accurate amounts of the flowable ingredients can be dispensed into the container.
Previous methods for dispensing flowable materials have suffered from many drawbacks. Primarily, the previous devices that have been designed to operate at speeds consistent with present day container filling operations have not been able to dispense the flowable materials as accurately as is necessary to produce a high quality product having consistent properties. On the other hand, previous dispenser systems that can accurately dispense flowable materials have not been able to keep up with the high-speed operation of advanced container filling operations.
The high speed and accurate dispensing of flowable granular materials presents several added operational problems that have not been overcome by previous dispenser systems. For example, the dispenser apparatus must be capable of maintaining the granular flowable material in a relatively moisture-free environment, particularly when the granular material may absorb the moisture, causing the material to cake and clog the conduits of the dispenser. In addition, many of the granular materials are abrasive and have a deleterious effect on the containers that receive the granular material, particularly when the granular material leaks out of the dispenser onto the exterior of the containers. The abrasiveness of the granular material has been particularly destructive of prior valving mechanisms that are constantly rubbing against the granular material.
In the fish canning industry, metering devices have been used in the past to dispense granular materials such as salt into the containers. The metering device generally includes a rotating disc having a plurality of holes in it. The disc rotates beneath a supply container of salt. As a hole passes beneath the supply container, salt falls out the supply container through the hole and into a container passing below. Normally, the disc is driven by the containers themselves, which requires complicated timing screws and drives to operate the dispenser. These types of devices have been less accurate than desired and also suffer from the problem of moisture contamination of the salt. The accuracy problem has been addressed by using salt in the form of preformed tablets. Unfortunately, such tablets are expensive to manufacture, which contributes to an increased cost of the final product. Another method of introducing salt into the containers is to pass the containers at a constant velocity beneath a constant volume stream of a brine solution. When using this method, the speed of the cans must be carefully controlled. Also, the equipment and containers are constantly being exposed to a corrosive brine solution.
Prior dispensing systems have been less than satisfactory in addressing the operational problems and design considerations described above. It would be desirable to provide a dispenser apparatus for flowable materials, particularly granular flowable materials, that is capable of operating at a high speed with a high degree of accuracy. Not only should the dispenser apparatus be fast and accurate, but is should also be capable of preventing contaminants from the ambient environment, such as moisture, from entering into the flowable material being dispensed by the dispensing appartus. Furthermore, the dispenser apparatus should be made of materials that are highly durable and resistant to chemical and physical degradation by the flowable materials.